1. Field of the Invention
The present invention relates generally to modeling devices for mounting teeth replications made from dental impressions to create a dental model of a patient's mouth and, more particularly, to an improved tray modeling system and articulator for producing such a dental model.
2. Description of the Prior Art
Numerous devices are known in the art for creating a working dental model of a patient's upper and lower teeth which are taken from dental impressions at the dentists office. The impression material is typically a malleable compound or a wax-type material which is molded around the patient's upper and lower teeth and gums and which creates a highly accurate negative impression of the teeth and surrounding areas. The impression is then filled with a powderized stone impression material or other appropriate material and is permitted to harden to form a highly accurate replication of the user's teeth. A series of metal dowel pins are inserted into the still hardening stone material which fills the impression at spaced intervals and correspond to the teeth or sections of teeth which are intended to be separated later on. The modeling device is normally engaged by the dowel pins to position and secure the dental impressions of the patient in such a manner so as to provide the dental professional with a highly accurate model of the user's mouth which will make possible the replication of certain of the patient's teeth in the preparation of dentures, crowns and the like.
The Vertex/KV 33 Corporation advertisement brochure teaches a dental impression model in which a powderized stone material similar to that used to create a conventional dental impression of the user's teeth is poured into an open mold. The stone material in the mold is allowed to harden to a certain degree, upon which a release spray coating is applied evenly over the exposed surface. The previously created dental impression is then immediately pressed into the mold base by engaging the dowel pins through the still somewhat malleable mold. The individual teeth or sections of teeth corresponding to the previously placed dowel pins may then be individually cut and separated from the stone base due to the release coating which prevents bonding of the hardening stone in the impression with that from the mold. The release coating allows the separated portions bonded around their respective dowel pins to be easily removed from the stone base and thus enables the specialist to begin preparing his or her model. An articulator, or universal mounting apparatus, is also employed to mount an upper impression model at a desired opposing orientation relative to a corresponding lower impression model to replicate the arrangement of the upper and lower rows of teeth.
While being fairly accurate in providing an accurate dental impression model, the Vertex model suffers from the shortcoming of being very time consuming to produce and necessitating a considerably large amount of stone substrate material, which again requires a considerable amount of setting time. An improvement of the Vertex device is taught by the Dental Ventures of America (DVA) model and die system which, in the place of a standard mold base, provides a predrilled base plate upon which the preformed dental impressions are attached. While the base plate of the DVA system reduces somewhat the time required to assemble the impression into the mold, the required time for producing the initial teeth replications from the impressions and the step of inserting the individual dowel pins into the hardening stone still largely offsets this advantage.
A marked improvement over the conventional impression models is provided by the Nu Logic E-Z Tray Model System which provides a collection of quarter and half trays which are shaped with cavities generally corresponding to the upper and lower impressions of the user's mouth and which define knurled ridges along both inwardly and outwardly facing edges which define the cavity. One or more keyed spine portions are snappingly engaged within groove shaped apertures formed in the bottom center and extending the length of the cavity. The keyed portion of the spine extends upwardly a distance into the cavity and, upon pouring of a quantity of the stone mix into the cavity, is bonded to the stone mix. The spines replace the conventional dowel pins and permit the impression and mold to be directly press fit onto the forming stone mix in the tray.
As further disclosed by the Nu Logic brochure, the model is separated from an overlaying dental impression which is press fit atop the drying stone in the base. The stone case with embedded spine may then be removed as an entire piece from the impression tray. The impression and spine may be cut by an appropriate saw into the desired sections of teeth which can then be remounted onto the tray by aligning the exterior knurled ridges of the stone case with the corresponding inwardly facing knurled ridges on the oppositely facing edges of the tray and then snapping the severed spine portions back in place along the guide slot formed in the bottom of the cavity.
While providing a considerable advantage over conventional dowel pin mounted models, the Nu-Logic device still suffers from the disadvantage of the knurled guiding edges or ridges formed along the inner and outer faces of the stone case being fairly fragile and vulnerable to being chipped or otherwise destroyed due to accident or misuse. Any resultant loss of the integrity of the guiding portions in the stone case would lessen the accuracy of the placement of the impression within the tray. Since there is also nothing aside from the general contour of the spine to prevent it from slipping relative to its axial slot, the opposing knurled portions are the only means of accurately reinserting the dental impressions into the tray.
The prior art further fails to teach an articulator for use with a dental impression model which is easily assembleable and disassembleable, capable of universally positioning and repositioning and locking into place an upper dental impression relative to a lower dental impression, and easily attached and disattached so as to be reusable with different impressions.